For example, suppose you catch yourself being tempted by a box of cookies. You could respond to this in a shame-based manner, or in a compassion-based manner:
Shame-based: you're already way too fat. You don't deserve those cookies so you shouldn't have them. It's no wonder you're not getting dates if this is how easily you're tempted.
Compassion-based: Wow, yes those cookies do look tasty, and it's no surprise you're tempted since you didn't sleep great last night and had a stressful morning to boot. It's natural and okay to have that desire for satiated fullness! But you don't have to let those feelings define your behaviour. Let's take a step back and think through the consequences of eating those cookies. Sure it will feel good at first. But the chances are that the good feelings will last less than an hour, after which you might feel regret about not sticking to your diet. Is it really worth the trade-off? Suddenly those cookies don't seem so tempting, do they?
The problem with shame-based feedback is that it simply adds to the negative feelings that a fat person is already likely to be having. Think of obesity and over-eating as an addiction to eating, on the same level as an addiction to gambling, drugs, or pornography. The behaviour is a crux, a way to get nice feeling in the short-term to avoid the work of dealing with difficult feelings. Over time, one's fear of those difficult feelings and dependence on the quick-fix grows. Adding another difficult feeling into the mix might help alleviate the behaviour in the short term, but won't reduce the emotional suffering or provide any basis for which to start learning to deal with the deeper cause.
[0] https://greatergood.berkeley.edu/topic/compassion/definition
The equivalent here would be banning the over-engineered foods that cause the problem. The common thing is the breaking of a habit. The harder it is to reenforce, the less it's done.
Look at where we were 50 years ago, and where we are today. 50 years ago, lots of bullying but fat kids were rare. Today we have far less bullying, and a ton of fat kids. I don't think it's working.